Abstract: Abstract: The main ways of crushed corn straw conveying are pneumatic conveying, screw conveying, belt conveying, scraper conveying, bucket lifting and chain conveying. Screw conveyor is widely used in the processing of rubbing and breaking corn straw due to its advantages of compact structure, flexible arrangement, good sealing and controllable feeding amount. However, due to the small density, viscosity and poor fluidity of crushed corn straw, the conveying performance is difficult to be guaranteed. There are some problems such as low productivity, high power consumption, easy jammed and serious abrasion in the process of conveying the agricultural fiber materials. In order to solve these problems, the theoretical analysis of conveying process about screw-pneumatic conveying device was carried out in this paper. The force of crushed corn straw during the conveying was analyzed. On this basis, the productivity model, power consumption model and specific power consumption were built. The screw flow transmission principle was considered, and the screw-pneumatic coupling conveying device was designed. The experimental platform was mainly composed of screw conveying device and pneumatic auxiliary conveying system. The parameters of the experimental platform were as follows: the conveying gap length was 2 500 mm, the diameter of the screw blade was 250 mm, the diameter of the center shaft was 60 mm, the screw pitch was 335 mm respectively, and the space between the screw blade and the shell was 5 to 8 mm. The pneumatic auxiliary conveying system was mainly composed of Y-shape nozzle holder with adjustable injection angle, nozzle, air compressor with maximum outlet pressure of 1.6 MPa, polypropylene random straight pipe with 10 mm diameter, 15° bending pipe and pressure gauge. The experiment materials were the corn straw after crushing through 9R-60 rubber and with less than 100 mm long, 2 to 8 mm wide, and 38% moisture content. Based on the performance index of specific power consumption, axial thrust, pressure on the screw blade and shell, the impacts of airflow velocity on transportation performance were analysed. The results showed that: When the screw pitch was 335 mm, the rotation speed was 100 r/min, and the feeding amount was 70 kg/min, within the range of airflow velocity 10～50 m/s, the greater the pressure on the outer edge, the greater the pressure on the screw blade. the pressure was different at different points of screw blade, the closer to the outlet, the greater the pressure was on all parts of the blade. On the same area of the shell, the pressure on the arc segment was greater than that of the vertical section. For different area of the shell, the pressure on the arc segment and vertical section of areaⅠwas greater than that of the areaⅡ. The pressure was different at different points of shell, the closer to the outlet, the greater the pressure was on all parts of the shell. The specific power consumption of the screw-pneumatic coupling conveying device first decreased and then increased with the increase of airflow velocity, when the airflow velocity was 20 m/s, the specific power consumption was the minimum, which was 10.78 W/kg, which was 8.3% lower than that of without airflow. The axial thrust, pressure on blade and shell decreased with the increase of airflow velocity, and was all less than that of without airflow.